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Seismic Tomographic Imaging of the Eastern Mediterranean Mantle: Implications for Terminal‐Stage Subduction, the Uplift of Anatolia, and the Development of the North Anatolian Fault

Kounoudis, R.; Bastow, I.D.; Ogden, C.S.; Goes, S.; Jenkins, J.; Grant, B.; Braham, C.

Authors

R. Kounoudis

I.D. Bastow

C.S. Ogden

S. Goes

B. Grant

C. Braham



Abstract

The Eastern Mediterranean captures the east-west transition from active subduction of Earth's oldest oceanic lithosphere to continental collision, making it an ideal location to study terminal-stage subduction. Asthenospheric- or subduction-related processes are the main candidates for the region's ∼2 km uplift and Miocene volcanism; however, their relative importance is debated. To address these issues, we present new P and S wave relative arrival-time tomographic models that reveal fast anomalies associated with an intact Aegean slab in the west, progressing to a fragmented, partially continental, Cyprean slab below central Anatolia. We resolve a gap between the Aegean and Cyprean slabs, and a horizontal tear in the Cyprean slab below the Central Anatolian Volcanic Province. Below eastern Anatolia, the completely detached “Bitlis” slab is characterized by fast wave speeds at ∼500 km depth. Assuming slab sinking rates mirror Arabia-Anatolia convergence rates, the Bitlis slab's location indicates an Oligocene (∼26 Ma) break-off. Results further reveal a strong velocity contrast across the North Anatolian Fault likely representing a 40–60 km decrease in lithospheric thickness from the Precambrian lithosphere north of the fault to a thinned Anatolian lithosphere in the south. Slow uppermost-mantle wave speeds below active volcanoes in eastern Anatolia, and ratios of P to S wave relative traveltimes, indicate a thin lithosphere and melt contributions. Positive central and eastern Anatolian residual topography requires additional support from hot/buoyant asthenosphere to maintain the 1–2 km elevation in addition to an almost absent lithospheric mantle. Small-scale fast velocity structures in the shallow mantle above the Bitlis slab may therefore be drips of Anatolian lithospheric mantle.

Citation

Kounoudis, R., Bastow, I., Ogden, C., Goes, S., Jenkins, J., Grant, B., & Braham, C. (2020). Seismic Tomographic Imaging of the Eastern Mediterranean Mantle: Implications for Terminal‐Stage Subduction, the Uplift of Anatolia, and the Development of the North Anatolian Fault. Geochemistry, Geophysics, Geosystems, 21(7), https://doi.org/10.1029/2020gc009009

Journal Article Type Article
Online Publication Date Jun 21, 2020
Publication Date 2020-07
Deposit Date Feb 4, 2021
Journal Geochemistry, Geophysics, Geosystems
Electronic ISSN 1525-2027
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 21
Issue 7
DOI https://doi.org/10.1029/2020gc009009
Public URL https://durham-repository.worktribe.com/output/1280833